Thing is, majority of people who read this kind-off series (especially in Japan), prefer Combat Action and Bed Action stuff.
To them, a Date chapter would feel boring and monotone.
I mean, we have other series under specific genre to cover stuff like Dating between couples and such. So, if anyone is interested in those stuff, they can read those series instead.
The focus of this series is "fighting in coliseum, and MC banging girls", that's all.
Just take a look at big series like Bleach, Naruto, Fairy Tail, Black Clover, etc.
Majority of their chapters focused only on Fights or some conspiracy, and the few chapters which didn't instead focused on some random Comedic routine or Fan-Service.
There weren't that many "Dating" stuff related plot in those series.
I bring those series up, because for majority of current generation of author's, those series had become an inspiration.